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Step 1 - Using a broom handle or wooden dowel, tap each floor tile. The hollow-sounding ones need re-bonding. Mark these tiles with a pencil. If tiles move when you apply downward pressure, cut through the surrounding grout line until the tile settles to the floor. If tiles are lifted off the floor (tented), number the tiles and remove them, clean the edges, and reset them in their original position on the floor.
Step 2 - Pick a masonry drill bit slightly narrower than the width of the grout joint (3/16" or 1/8"). Drill holes in 4-8 places in the grout around each loose or hollow tile you have marked.
Step 3 - Using a rubber mallet, carefully hammer a small area (4-6) tiles to force the subsurface dust and debris out through the holes in the grout. Brush out and vacuum these holes thoroughly.
Step 4 - Find the place on the plastic tip of the Inject-A-Floor System cartridge where it will fit snugly into the holes but does not go below the base of the tile. Cut the tip straight across at that point.
Step 5 - Inject the adhesive into each hole. Expect some initial resistance but extreme force is not necessary. Keep tapping the files with the wooden handle to monitor the flow of solution and with the rubber mallet to keep the surrounding holes clear of surface debris.
Step 6 - After injecting all the holes, place-water-filled buckets on all the re-bounded tiles. Wipe away excess adhesive with sponge and water. Keep the buckets in place for 12 hours.
Step 7 - Clean the area of all excess adhesive with IAF Choice All Purpose Cleaner diluted 1 cup to a gallon of water. Then fill in the holes with matching grout and blend into existing grout joint. After grout is dry, mop with IAF Green Cleaner, diluted 1-cup cleaner to 2 gallons of water.